Tubular coupling element for producing a glued joint with a fluid line

ABSTRACT

A tubular coupling element for producing a glued joint with a fluid line and a method for producing such a glued joint. The coupling element includes an inner tube that is insertable into a fluid line and an outer tube that is constructed concentric to the inner tube and integrally connected to the rear end of the inner tube by a connecting wall. An annular gap is present between the two tubes and is designed to receive an end section of the fluid line and a hot-melt type adhesive in a compacted solid form shaped as a ring. A connection between the coupling element and the fluid lines can be easily established by first introducing the adhesive in the annular gap and then melting it by rapidly supplying heat while the end section of the fluid line is pressed into the annular gap of the coupling element.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention pertains to a tubular coupling element for producing aglued joint with a fluid line. The coupling element includes an innertube that can be inserted into a fluid line and an outer tube that isconcentric to the inner tube and integrally formed on the rear end ofthe inner tube with a closed ring.

2. Reference to Related Art

A coupling element is known from DE 26 03 299 A1. In that case, anannular gap between an inner tube and an outer tube is filled with aliquid adhesive so that the respective intermediate spaces between thefluid line and the inner tube and the outer tube are entirely filled outafter the fluid line is inserted. The adhesive has two liquid componentsthat are held in the annular gap by removable cover films. Theutilization of liquid adhesive components has the disadvantage in thatthe films initially need to be removed at the construction site beforethe tubular end of the fluid line can be inserted into the annular gap.In addition, the tubular end of the fluid line and the coupling elementneed to be held in an axially aligned position until the adhesive hashardened. One also needs to proceed very carefully when filling in theannular gap with the adhesive components by correctly metering thecomponents and by sealing the annular gap in an air-tight fashion.

A tubular coupling element is also known from DE 44 42 407 C1. In thatcase, an annular gap is filled with a hardenable sealing or bindingagent and then closed with a removable air-tight cover. However, thismethod also results in the aforementioned disadvantages in that thecover film initially needs to be removed at the construction site beforethe tubular end of the fluid line can be inserted into the annular gapto produce the glued joint.

SUMMARY OF THE INVENTION

The present invention is directed to the filling of an annular gap witha suitable adhesive in such a way that a coupling element can be rapidlyand easily connected to the end section of a fluid line.

The objective is attained by filling an annular gap between an innertube and an outer tube with a dry hot-melt adhesive that is compactedinto the shape of a solid ring.

A glued joint between the end of a fluid line and the coupling elementcan be produced in a much simpler and less expensive fashion than withthe state of the art. Since the hot-melt adhesive is introduced into thegap in the form of a solid compacted ring, it can be retained thereinwithout cover elements and reactivated for use at any time by applyingheat. A method according to the invention makes it possible to easilyconnect fluid lines and coupling elements to one another. The method isparticularly advantageous when the coupling element is constructed of aplastic material and the fluid line is constructed of an aluminum tubeor a metal tube that is encased with plastic as is increasingly utilizedin modern technology.

The invention also teaches various advantageous additional developmentsthat serve for achieving the individual advantages described below.

Specifically, the design of the inner tube serves for producing acentered contact with the end section of the fluid line while thehot-melt adhesive is able to distribute between longitudinal ribs.

The design of the outer tube makes it possible for the adhesive insertedbetween the inner tube and the outer tube to flow outward along the ribswhen it is subjected to heat such that a uniform distribution of theadhesive is ensured.

Finally, a method for producing a glued joint advantageously describeshow the ring of adhesive introduced into the annular gap can be rapidlyheated while the fluid line is inserted, and how the end of the fluidline can be properly pressed into the melting adhesive.

BRIEF DESCRIPTION OF THE DRAWINGS

One preferred embodiment of the invention is illustrated in the figuresand described in greater detail below, wherein:

FIG. 1 is a side view of a coupling housing with a partial sectionthrough a coupling element along the line I—I in FIG. 2;

FIG. 2 is a lateral section view through the coupling element along theline II—II in FIG. 1;

FIG. 3 is a longitudinal section view through a compacted adhesive ringto be inserted into an annular gap of the coupling element;

FIG. 4 is a schematic presentation of a coupling housing with aninserted adhesive ring;

FIGS. 5 and 6 are side views demonstrating a sequence of producing aglued joint between the coupling element and the fluid line; and

FIG. 7 shows a side view of a finished glued joint between the fluidline and the coupling element.

DETAILED DESCRIPTION

Referring now to FIGS. 1 and 2, there is shown a tubular couplingelement 1 that is integrally connected to a coupling housing 2. Asindicated in FIG. 7, the coupling element 1 serves for producing a gluedjoint with a fluid line 3 that, for example, includes an aluminum tubeor another suitable metal tube. The coupling element 1 may, however,also be integrally formed on a plug-in element (that is not illustratedin the figures) and conventionally inserted into the coupling housing 2in order to produce a separable plug-type connection.

Still referring to FIGS. 1 and 2, the coupling element 1 includes aninner tube 4 that is inserted into a free end 20 of the fluid line 3 andan outer tube 5 that is concentric to the inner tube 4 and connected tothe rear end of the inner tube 4 by a connecting wall 6. An outersurface 7 of the inner tube 4 preferably includes at least threelongitudinal ribs 8 that serve for producing a centered contact with theinner wall 9 of the fluid line 3 when it is pushed over the inner tube 4(FIG. 6).

As seen in FIG. 2, the outer tube 5 is provided with a series of axiallyparallel grooves 10 having peaks 11 that are distributed over the innersurface of the outer tube 5. The inside diameter of the inner surfacebetween opposing peaks 11 is slightly larger than the outside diameter Dof the fluid line 3. The length of the outer tube 5 preferablycorresponds approximately to the outside diameter D of the fluid line 3such that the inner tube 4 is longer than the outer tube 5 byapproximately one-half.

Referring now to FIGS. 1–3, to produce a glued joint between the tubularcoupling element 1 and the fluid line 3, an annular gap 13 between theinner tube 4 and the outer tube 5 is filled with a hot-melt adhesive toapproximately half its depth. The hot-melt adhesive is introduced intothe annular gap 13 in the form of a compacted solid ring 14 (FIG. 3).The outside diameter D1 of the ring 14 is slightly smaller than theinside diameter d2 of the peaks 11, and the inside diameter d1 of thering 14 corresponds approximately to an inside diameter d of the fluidline 3. The width B of the ring 14 has such dimensions that the ring 14fills out approximately half the depth of the annular gap 13.

Referring now to FIGS. 3 and 4, upon inserting the ring 14 into theannular gap 13 in the direction of the arrow P, the ring 14 is pressedinto the gap 13 until it contacts the connecting wall 6 (FIG. 4). Thering 14 is preferably pressed into the gap 13 with the aid of anauxiliary tool 15 that contains circumferentially distributed pressingelements 16. Following insertion of the ring 14, the coupling element 1is ready for gluing to the free end 20 of the fluid line 3.

As shown in FIGS. 5–7, the coupling housing 2 is initially held inposition with a coupling holder 17 while the fluid line 3 is moved intoa position opposite the coupling housing 2 axis through the use of atube holder 18. An induction coil 19 is then placed around the free end20 of the fluid line 3 such that the tubular end 20 of the fluid line ispreheated (FIG. 5).

The coupling element 1 is pressed on the free end 20 of the fluid line 3in the direction of the arrow M by means of the holder 17 and issurrounded by the induction coil 19. The adhesive ring 14 melts due tothe thermal effect generated by the induction coil. While the tubularend 20 of the fluid line 3 penetrates into the hot-melt adhesive, theadhesive is displaced on the inner wall 9 and the outer wall 12 alongthe ribs 8 and the grooves 10 in the inserting direction M. This causesthe intermediate spaces between the tubular end 20 of the fluid line andthe coupling element 1 to be completely filled out with the hot-meltadhesive (FIG. 6).

After the hot-melt adhesive has set and pre-hardened, the process ofconnecting the coupling element 1 and the fluid line 3 is concluded suchthat the holders 17 and 18 can be removed and the adhesive permitted tocure (FIG. 7). The coupling 2 with the fluid line 3 glued thereto canthen be transported to the site of its intended use.

In the embodiment shown, the tube holder 18 is shown as a solid bodywith a blind hole into which the fluid line 3 is inserted with itsoutgoing end. However, the tube holder may also include a clampingelement that surrounds the fluid line 3, e.g., a pipe clamp. This isparticularly advantageous if the fluid line 3 has a greater length thanshown in FIGS. 5 and 6.

1. A tubular coupling element for producing a glued joint with a fluidline, said tubular coupling element comprising: an inner tube having afront end and a rear end, wherein said front end is insertable into afluid line; an outer tube having a front end and a rear end, whereinsaid outer tube is concentric to said inner tube and a length of thefront end of said inner tube is longer than a length of the front end ofsaid outer tube; a linear connecting wall interconnecting said innertube rear end to said outer tube rear end, wherein said outer tube, saidconnecting wall and said inner tube define one cylindrically shapedannular gap; and a solid ring of hot melt adhesive disposed within theannular gap and positioned against said connecting wall, such that saidsolid ring of hot melt adhesive occupies less than the full volume ofthe annular gap.
 2. The tubular coupling element of claim 1, whereinsaid inner tube further includes an outer surface, having a plurality oflongitudinal ribs for producing a centered contact with an inner wall ofthe fluid line.
 3. The tubular coupling element of claim 1, wherein saidouter tube further includes an inner surface having a plurality ofaxially parallel grooves distributed over a circumference of said innersurface, wherein said grooves have peaks with an inside diameter that islarger than an outside diameter of the fluid line.
 4. The tubularcoupling element of claim 1, wherein a length of said outer tube isapproximately equal to an outside diameter of the fluid line and saidinner tube is longer than said outer tube by about one-half the lengthof said outer tube.
 5. A tubular coupling element for producing a gluedjoint with a fluid line, said tubular coupling element comprising: aninner tube having a front end and a rear end, wherein said front end isinsertable into a fluid line; an outer tube having a front end and arear end, wherein said outer tube is concentric to said inner tube and alength of the front end of said inner tube is longer than a length ofthe front end of said outer tube; a linear connecting wallinterconnecting said inner tube rear end and said outer tube rear end,wherein said outer tube, said connecting wall and said inner tube defineone cylindrically shaped annular gap; and a solid ring of hot meltadhesive disposed within the annular gap and positioned against saidconnecting wall, wherein said solid ring of hot melt adhesive fillsapproximately one-half a depth of the annular gap.
 6. A tubular couplingelement for producing a glued joint with a fluid line, said tubularcoupling element comprising: an inner tube having a front end and a rearend, wherein said front end is insertable into a fluid line; an outertube having a front end and a rear end and an inner surface having aplurality of axially parallel grooves distributed over a circumferenceof said inner surface, wherein said outer tube is concentric to saidinner tube; a linear connecting wall interconnecting said inner tuberear end to said outer tube rear end, wherein said outer tube, saidconnecting wall and said inner tube define one cylindrically shapedannular gap; and a solid ring of dry hot-melt adhesive disposed withinthe annular gap and positioned against said connecting wall, whereinsaid solid ring of adhesive fills about one-half a depth of the annulargap.
 7. A tubular coupling element for producing a glued joint with afluid line, said tubular coupling element comprising: an inner tube thatis insertable into the fluid line wherein said inner tube includes afront end and a rear end, and an outer surface having a plurality oflongitudinal ribs for producing a centered contact with the fluid line;an outer tube having a front end and a rear end and having an innersurface having a plurality of axially parallel grooves distributed overa circumference of said inner surface, said grooves having peaks with aninside diameter that is larger than an outside diameter of the fluidline, wherein said outer tube is concentric to said inner tube; a linearconnecting wall interconnecting said inner tube rear end to said outertube rear end, wherein said outer tube, connecting wall and said innertube define one cylindrically shaped annular gap; and a solid ring ofdry hot-melt adhesive disposed within the annular gap and positionedagainst said connecting wall, wherein said solid ring of adhesive fillsabout one-half a depth of the annular gap.
 8. A method for producing aglued joint between a tubular coupling element and a fluid line, saidmethod comprising the steps of: providing a tubular coupling elementincluding an inner tube having a front end and a rear end, and the frontend is insertable into a fluid line, a connecting wall secured to theinner tube rear end and an outer tube having a front end and a rear end,and extending from the connecting wall, wherein the outer tube isconcentric to the inner tube, and the inner tube, outer tube andconnecting wall define an annular gap; providing a solid ring of hotmelt adhesive; pressing the solid ring of adhesive in the annular gapagainst the connecting wall, wherein the solid ring of adhesive fillsabout one-half the annular gap; applying heat to the tubular couplingelement so as to melt the solid ring of adhesive; inserting a free endof the fluid line into the melting adhesive in the annular gap such thatthe melting adhesive flows around the free end of the fluid line to fillan intermediate space between the free end of the fluid line and thecoupling element.
 9. The method of claim 8, wherein the solid ring ofadhesive has an inside diameter corresponding to an inside diameter ofthe fluid line, and an outside diameter slightly smaller than an insidediameter of the outer tube.
 10. The method of claim 8, furthercomprising the steps of using an induction coil to preheat a free end ofthe fluid line and melt the solid ring of adhesive.
 11. The method ofclaim 10, wherein the free end of the fluid line is pushed onto thecoupling element together with the induction coil.
 12. A method forproducing a glued joint between a tubular coupling element and a fluidline, said method comprising the steps of: providing a tubular couplingelement including an inner tube having a front end, a rear end, and anouter surface, and the front end is insertable into a fluid line,wherein the outer surface includes a plurality of longitudinal ribs forproducing a centered contact with an inner wall of the fluid line, aconnecting wall is secured to the rear end of the inner tube, and anouter tube having a front end and a rear end extending from theconnecting wall that is concentric to the inner tube and has an innersurface including a plurality of axially parallel grooves distributedover a circumference of the inner surface, wherein the outer tube, innertube and connecting wall define an annular gap; providing a solid ringof hot melt adhesive; pressing the solid ring of adhesive in the annulargap against the connecting wall, wherein the solid ring of adhesivefills about one-half the annular gap; applying heat to the tubularcoupling element so as to melt the solid ring of adhesive; and insertinga free end of the fluid line into the melting adhesive in the annulargap such that the melting ring of adhesive flows around the free end ofthe fluid line such that a small portion of the adhesive flows betweenthe fluid line and the inner tube and a predominant portion of theadhesive flows between the fluid line and the outer tube.
 13. The methodof claim 12, wherein the solid ring of adhesive has an inside diametercorresponding to an inside diameter of the fluid line, and an outsidediameter slightly smaller than an inside diameter of the outer tube. 14.The method of claim 12, further comprising the steps of using aninduction coil to preheat a free end of the fluid line and melt thesolid ring of adhesive.
 15. The method of claim 14, wherein the free endof the fluid line is pushed onto the coupling element together with theinduction coil.